The Pioneering Work On Linear Fresnel Reflector ... - GSES

One must not believe, despite the silence of modern writings, that the idea of using heat for mechanical
operations is recent. On the contrary, one must recognize that this idea is very ancient and in its slow
development across the centuries it has given birth to various curious devices.
In 1878 Mouchot exhibited at the Universal Exposition in Paris what is commonly known to be the first and
largest machine in the world to produce solar steam. Mouchot’s sun machine was subsequently improved by
his assistant Abel Pifre, by adopting a spherical parabolic solar collector to power a printing press [1].
Fig. 1. Left, Augustine Mouchot’s sun machine, the largest of its time, on display at the Universal
Exposition in Paris in 1878. Right, Abel Pifre’s solar-powered printing press, exhibited at the Gardens
of the Tuileries in Paris 1880 [1] [5].
These developments in France were noted in several other countries, especially in those lacking in coal and
other fossil fuels. In Italy, Alessandro Battaglia (1842 – n.a.), an Italian engineer from Acqui Terme, thought
that the Mouchot-Pifre designs, despite their merits, also had several inherent limitations that he illustrated in
1884 at the Istituto di Incoraggiamento di Napoli (Encouragement Institute of Naples) [6].
In his paper “Sul modo e sulla convenienza di utilizzare il calor solare per le macchine a vapore” (On the
methods and convenience of using solar heat for steam engines) Battaglia illustrated the limitations of the
Mouchot-Pifre designs:
- It is not possible to build boilers of sufficient capacity to power industrial engines due to the fact
that the boiler is mounted on the tracking collector, which limits its size;
- The boiler loses its heat easily because it is exposed to open air and cannot be insulated and
protected;
- The tracking collector, as a single surface, is also limited in its total area.
To overcome these limitations, Battaglia proposed separating the boiler from the collecting reflector area. He
proposed a horizontal cylindrical boiler 30 meters in length and 1 meter in diameter, enclosed inside an
insulating brick oven with a window of the same length as the boiler and 1 meter in height, facing a separate
collecting reflector area made up of 1250 small flat mirrors, one square meter each, distributed in 42 rows of
30 mirrors each. The system, which he described in economic and technical details, was estimated to have an
output of 50 HP (37.3 kW), with an approximate cost of 100,000 lire in 1884 or 420,233 in 2008 Euros.
In 1884, Battaglia applied for a patent for his invention as a “Collettore multiplo solare” (Multiple Solar
Collector), though with a boiler of just 10 meters and only 250 of the 1250 flat mirrors indicated in his paper.
Battaglia’s patent is illustrated in the following drawings in figure 2, courtesy of the Central State Archive,
Rome, Italy.
The purpose of Battaglia’s invention, as explained in his patent, is “to collect the solar rays that strike a
specific portion of the earth’s surface at any latitude, and to reflect them, concentrated in a specially shaped
beam, onto a specific surface of limited size, in order to obtain a high temperature and a quantity of calories
capable of causing a specific effect, at a cost relatively small for the size of the reflecting surface. The
surfaces that receive and reflect the solar rays are metallic, silver-coated and burnished. The reflection must
be continuous; that is, it must be aimed at the same point every day of the year, from sunrise to sunset [7].”